<VV> LM turbos and no lower shrouds

Eric S. Eberhard flash at vicsmba.com
Mon Oct 24 19:51:55 EDT 2011

Thanks == now I don't quite feel like the village idiot when there 
are a couple of us that agree :-)  E

At 04:24 PM 10/24/2011, Mark Durham wrote:
>I must agree, I think GM did an excellent job with the engine, its
>pretty much bullet proof. Even temps work in aircraft, in fact people
>who pay attention to that get a lot more life out of their engines. GM
>figured this out and used the shrouds to keep a even temp in uneven rpm
>and power situations. I do not like that the oil cooler dumps into that
>hot air, I think the engines would do even better if the oil cooler air
>went out the back, maybe with its own thermostat for getting the oil to
>temp, but other than that, its a good durable motor.
>I do remember I compensated for a overly active fuel pump by removing
>the lower shrouds. Got tired of flood starting it. It did better when
>not so hot. But I put the shrouds back on after adding a pressure
>regulator to the fuel circuit. And it was fine.
>Mark Durham
>Sent from my Windows Phone From: Eric S. Eberhard
>Sent: Monday, October 24, 2011 2:43 PM
>To: Mark Durham; virtualvairs at corvair.org
>Subject: RE: <VV> LM turbos and no lower shrouds
>I agreed all the way through the sentence ending with "design
>limits"  :-)  I believe that more consistent temps with the correct
>range are a desired end result and that just making it run colder and
>inconsistently and harder to warm up ... not so good.  E
>At 08:48 AM 10/23/2011, Mark Durham wrote:
> >Eric and all; it is true that the stock systems were designed to
> >provide reasonable temp, but there are two sets of baffles/shrouds that
> >are worthy of note here, and they both have different functions.
> >First, the shrouds that box in the front and back portions of the
> >engine, the design of the heads, the turkey roaster and the inner
> >cylinder baffles direct the airflow to keep the engine cool. The bottom
> >shrouds inhibit that flow when temps are below a certain value so the
> >engine temps stay in a determined range so heat is available and so
> >engine temps are more consistent. This extends engine life because it
> >keeps temp in design limits.
> >Turbos do raise the temps and turbo engines, in airplanes and cars, air
> >cooled ones, have a shorter life span, or in my mechanic lingo, shorter
> >TBO, time between overhauls.
> >I found my em 62 with a 270 cam and stroked to a 64 110 runs smoother
> >and cooler and hot starts better when I have the lower shrouds off in
> >the 90 plus temps we get in the summer when I Don't need heat. Mark
> >Durham
> >
> >Sent from my Windows Phone From: Eric S. Eberhard
> >Sent: Saturday, October 22, 2011 11:30 PM
> >To: virtualvairs at corvair.org
> >Subject: <VV> LM turbos and no lower shrouds
> >
> >
> >I am always puzzled by this discussion which comes up every so
> >often.  The car was designed well from the factory.  If you have
> >everything correct -- all the shrouds as well as seals and so forth,
> >there is no better system.  I am in AZ, totally bone-stock, at
> >altitude (3500-8000 feet), summer temps of 110 ... and I NEVER have
> >even gotten remotely close to overheating.  Our speed limit is 75 and
> >I can go up a 6% grade at 80, no over heating.  From my 3500 to 7500
> >feet happens in 6 miles, no overheat even at 80.
> >
> >I believe that those that overheat and think they need to
> >remove/modify shrouds simply have other problem they are compensating
> >for.  Mine is a 62 EM and perhaps it is different, but I have had to
> >EM turbos as well and neither ever had a heating problem.
> >And we get 20 degrees in the winter, so having those shrouds on then
> >is crucial and I don't need the hassle of swapping them on and off.
> >
> >One writer pointed out the correct heat is required for quick
> >boost.  Correct.  Some people even wrap their exhaust to push temp
> >even higher, for that reason.  Some people mistakenly use a "free
> >flowing" muffler which actually reduces boost and is bad.  I used an
> >NOS turbo muffler.
> >
> >Keep it stock and it will be absolutely reliable (my only mods are
> >electronic ignition and related upgrades).
> >
> >If you have heating problems -- are your plugs too hot?  I use Nology
> >Silverstone plugs and they perform very well with a 38 gap and hot
> >ignition, no overheating.  They are made for vintage cars.  They are
> >expensive, but I have over 30k on them and they are clean as a whistle.
> >
> >BTW -- opinions are like belly buttons and so I have one.  I respect
> >others, as other people have done neat things.  I am not a good
> >enough amateur mechanic to re-engineer things.  But I believe a
> >properly set up stock system -- not all that hard to achieve -- is
> >going to be reliable.  Doing the ignition and putting a Judson on one
> >of my cars is sort of the limit of my explorations.  However, my
> >Spyder always has instant boost (no lag), boosts at 2000 rpm in 4th,
> >pulls to redline, and I can't overheat it.
> >
> >So if you are in the mood, you might try making it factory spec
> >first, seeing how that goes, and then modify.  Otherwise, you might
> >mask a problem that later gets ugly.
> >
> >Eric
> >
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> >  _______________________________________________
>Eric S. Eberhard
>(928) 567-3727          Voice
>(928) 567-6122          Fax
>(928) 301-7537                           Cell
>Vertical Integrated Computer Systems, LLC
>Metropolis Support, LLC
>For Metropolis support and VICS MBA Support!!!!    http://www.vicsmba.com
>For pictures:  http://www.vicsmba.com/ourpics/index.html
>(You can see why we love this state :-) )

Eric S. Eberhard
(928) 567-3727          Voice
(928) 567-6122          Fax
(928) 301-7537                           Cell

Vertical Integrated Computer Systems, LLC
Metropolis Support, LLC

For Metropolis support and VICS MBA Support!!!!    http://www.vicsmba.com

For pictures:  http://www.vicsmba.com/ourpics/index.html

(You can see why we love this state :-) )  

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